The present invention relates to a color copying machine using more than one recording color.
Conventional color copying machines provide a desired image by optically separating image information of the original and by combining two or more recording colors. In xerographic color copying using three color toners, i.e., yellow, cyan and magenta, color separation is effected with red, blue and green filters and the densities of the three colors, yellow, cyan and magenta, are properly controlled depending upon the color to be reproduced. While halftone color or mixed colors can be easily reproduced by such color copiers, the failure to transfer the recording colors in registry with one another results in very poor image quality. This defect frequently occurs in the circular portion of a letter, but it has been very difficult to avoid this problem by color registration, i.e. by accurately superposing the transferred colors in their respective positions on the receiving sheet. In ordinary color originals, the greater part of the image information is assumed by black or while colors (achromatic colors) and the chromatic area does not have to achieve the maximum color fidelity of the original, and, as is often the case with a multi-colored graph or a colored letter, the chromatic region may only have to be visually distinguished from other areas.